A sensor network system wirelessly collects sensor data from various sensors. In the sensor network system, sensor nodes periodically send sensor data to a sink node.
However, as the number of sensor nodes is increased, an amount of data transmission is geometrically increased. As the amount of data transmission is increased, energy consumption is increased. Further, delay of communication traffic occurs, thereby, reliability of data may be damaged. Therefore, it is required to significantly reduce the amount of data transmission without greatly lowering the reliability of the data.